Combustion turbines are well known in the art as having a compressor section for supplying a flow of compressed combustion air, a combustor section for burning a fuel in the compressed air, and a turbine section for extracting thermal energy from the combustion air and converting that energy into mechanical energy in the form of a shaft rotation. Many parts of the combustor section and turbine section are exposed directly to the hot combustion gases, for example the combustor, the transition duct between the combustor and the turbine section, the turbine stationary vanes, rotating blades and surrounding ring segments.
It is also known that the power and efficiency of a combustion turbine may be improved by increasing the firing temperature of the fuel or fuel mixture traveling through the combustor basket of the combustor section. As a result, modern, high efficiency combustion turbines may have firing temperatures of 1600° C. or more, which is well in excess of the safe operating temperature of the structural materials used to fabricate the components of the combustor section. Accordingly, several methods have been developed to provide cooling for such components.
One known method of cooling the body of the combustor basket is to force a cooling medium, preferably air, through an annular gap having a plurality of plate fins between an inner and outer wall of the combustor basket. As shown in prior Art FIG. 1, for example, known combustor basket 10 includes an exterior wall 12 and an interior wall 14 and an annular gap 16 therebetween. Within the annular gap 16, there is located a plurality of plate or cooling fins 18 having a plurality of heat transfer plates 20 disposed along the direction of the flowing air within the annular gap 16 to transfer heat from the walls 12, 14 of the combustor basket to the flowing air by convection. This method of cooling the combustor basket body requires a significant amount of air to be added to the combustor section and the combustor basket material may still have a limited maximum temperature allowance. Further, since it is desirable to increase combustion temperatures to increase the efficiency of the combustor, known combustors with the aforementioned plate fin design are limited in the efficiency they can obtain. Even further, the method of manufacturing such baskets having plate fins can be very costly and requires a large number of components. Thus, there is a need for a combustor basket that requires less air to be cooled, can withstand relatively high operating temperatures, and that is able to be manufactured easily.